How to calibrate a digital thermometer

Nick DavisUpdated February 21, 2017

Available in a variety of models and sizes, digital thermometers measure temperature and outputs the measurement on a display similar to a calculator screen. The instruments are used in medical, food, human, industrial and other environments. Like their non-digital counterparts, you need to calibrate your digital thermometer to ensure it provides an accurate reading. Calibration is needed before using the thermometer for the first time; if you use the thermometer to measure both hot and cold temperatures; if you drop the thermometer; and if you use the digital thermometer multiple times during the same day.

Calibrating with ice

Fill an insulated glass with crushed ice from a ice machine or by grinding ice cubes with a blender.

Add 120 ml (1/2 cup) of water from a sink. Let the ice mixture sit for five minutes.

Insert the sensing end of your digital thermometer into the centre of the ice mixture. Push the thermometer to the middle of the glass.

Let the digital thermometer sit in the ice mixture for 30 seconds. The thermometer should display 0 degrees on its display.

If the thermometer reads “Error” or another temperature, repeat steps 3 and 4.

Press the “Reset” button on the side of your thermometer. Your digital thermometer is now calibrated.

Calibrating with boiling water

Fill a pot with 720 ml (3 cups) of water from a sink. Bring the water to a boil on a stove, burner or other heat source. Turn off the pot once the water is boiling.

Insert the sensing end of your digital thermometer into the centre of the hot water. Push the thermometer to the middle of the water.

Let the digital thermometer sit in the water for 30 seconds. The thermometer should display 100 degrees on its display, if you are at 305 metres elevation or less.

If the thermometer reads “Error” or another temperature, repeat steps 2 and 3.

Press the “Reset” button on the side of your thermometer. Your digital thermometer is now calibrated.

Tip

If completing steps in the “Calibrating – Using Boiling Water” section and you are at an elevation between 305 and 610 metres, the temperature to calibrate your digital thermometer at is 98.9 degrees C; between 610 and 915 metres, calibrate at 97.8 degrees C; between 915 and 1,220 metres, 96.9 degrees C; between 1,220 and 1,525 metres, 95.8 degrees C; between 1,525 and 1,830 metres, 94.9 degrees C; and 2,440 metres and higher, 91.9 degrees C. Using the ice mixture method provides the most accurate calibration.

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About the Author

Nick Davis is a freelance writer specializing in technical, travel and entertainment articles. He holds a bachelor's degree in journalism from the University of Memphis and an associate degree in computer information systems from the State Technical Institute at Memphis. His work has appeared in "Elite Memphis" and "The Daily Helmsman" in Memphis, Tenn. He is currently living in Albuquerque, N.M.